This application is a continuation of PCT/IB99/00579 filed Apr. 6, 1999, which claims priority from South African patent application 98/2910 filed Apr. 6, 1998.
This invention relates to a method of positioning a cursor on the display screen of a computer, under control of an operator, and to means for carrying out the method.
The term xe2x80x9ccursorxe2x80x9d is to be understood as encompassing a pointer or other device or symbol that is displayed on the display screen of a computer and can be moved about on the screen under control of the operator. A cursor could, for example, be used to point at or designate an icon or attribute displayed on the display screen and that is to be selected.
According to the invention there is provided a method of positioning a cursor on the display screen of a computer, under control of an operator, the method comprising the steps of:
establishing a field about a movable body part of the operator;
sensing the strength of the field at one or more predetermined positions in a fixed reference frame, thereby to provide a control variable corresponding to the position of the body part in the reference frame; and
positioning the cursor on the display screen in response to the control variable.
The arrangement may then be such that the movable body part acts as a radiating antenna.
The movable body part may be one of the hands of the operator.
Where the movable body part is one of the hands of the operator, the field may be established by injecting an electrical signal into the operator""s body via the other hand of the operator.
The strength of the field may be sensed by means of a first pair of position-sensing electrodes spaced apart in a first direction in the reference frame, to provide a first control variable corresponding to the position of the body part in the first direction, and a second pair of position-sensing electrodes spaced apart in a second direction perpendicular to the first direction, to provide a second control variable corresponding to the position of the body
part in the second direction.
The term xe2x80x9celectrodexe2x80x9d is to be interpreted in a broad sense so as to include also an antenna.
The cursor may be positioned by moving it to a position on the display screen corresponding to the position of the body part in the reference frame, if the body part is within an imaginary boundary in the reference frame, and by continuing to mo % ee it along a line corresponding to the direction in which the body part approached the boundary, if the body part is at or beyond the boundary.
Further according to the invention there is provided a computer system which comprises a display screen, a keyboard for entry of data into the system, and positioning means for controlling the position of a cursor on the display screen, the positioning means comprising:
position-sensing electrodes placed in a fixed reference frame, for sensing the strength of a field established about a movable body part of an operator and thereby to provide a control variable corresponding to the position of the body part in the reference frame; and
control means operative in response to the control variable to position the cursor on the display screen in accordance with the position of the body part in the reference frame.
Where said body part is one of the hands of the operator, the position-sensing electrodes may be so arranged with respect to the keyboard that the operator can control the position of the cursor by moving said hand in a hovering manner over the keyboard.
The system may further comprise a signal generator for generating an alternating electrical signal, and an injection electrode for injecting the electrical signal into the body of the operator and so establish the electrical field about said movable body part. Where said movable body part is one of the hands of the operator, the injection electrode may be arranged to inject the electrical signal into the body of the operator via the other hand of the operator.
The system may further comprise one or more click switches for operation by the operator. The click switch or switches may be arranged to be operated by said other hand of the operator.
The system may further comprise a conventional pointing device, and selection means for enabling the operator to select the conventional pointing device for controlling the position of the cursor on the display screen.
The invention extends to an accessory for use in positioning a cursor on the display screen of a computer, under control of an operator, the accessory comprising:
signal generating means for generating an electrical signal;
an injection electrode coupled to the signal generating means, for injecting the electrical signal into the body of the operator, thereby to establish a field about a movable body part of the operator;
position-sensing electrodes for placement in a fixed reference frame, for sensing the strength of the electrical field; and
means coupled to the position-sensing electrodes for generating a control variable corresponding to the position of the body part in the reference frame, whereby the cursor can be positioned in response to the control variable.